Among the conventionally-known working machines are ones which include a gas engine mounted on the machine body, a handle base extending rearwardly from the machine body and a hollow storage section provided in the handle base for accommodating a cassette gas canister, and in which the hollow storage section is closed with a gas canister cover. One example of such working machines is disclosed in Japanese Patent Application Laid-Open Publication No. HEI-11-170876 (JP 11-170876 A).
The gas-engine-mounted working machine of JP 11-170876 A includes a mouthpiece support section for supporting a mouthpiece portion of the cassette gas canister, and the mouthpiece support section has a nozzle receiving port for receiving a jet nozzle of the cassette gas canister. When not in use, the gas-engine-mounted working machine is stored with the cassette gas canister detached from the hollow storage section after the canister mouthpiece portion being detached from the mouthpiece support section. Therefore, during storage of the gas-engine-mounted working machine, foreign matter, such as dust, may undesirably enter, through hollow storage section, the nozzle receiving port. As a measure for avoiding such entry of foreign matter, it is conceivable to construct the entire hollow storage section into a highly sealed structure, which is, however, extremely difficult because the hollow storage section is a space relatively great in size.